Elucidation of the etiology and characteristics of pink urine in young healthy subjects

Propofol-Associated Urine Discoloration: Systematic Literature Review

INTRODUCTION

Propofol occasionally induces a green or pink-cloudy urine discoloration. A lesser-known effect is green discoloration of hair, milk, liver, or stool. We aimed to gain insight into the features of these disturbances.

METHODS

The terms ("propofol" OR "fospropofol") AND ("green" OR "pink" OR "cloudy" OR "pink-cloudy") were searched in Excerpta Medica, MEDLINE/PubMed®, and Web of Sciences databases, with no language limit, from inception up to February 2023 (CRD4202236804). Articles reporting individually documented cases were retained, and data were extracted using a checklist.

RESULTS

Seventy-seven original reports documented 95 cases (including 13 subjects ≤18 years of age). Completeness of reporting was satisfactory in 33, good in 35, and excellent in 27 cases. Propofol-associated green urine discoloration was observed in 54 patients. In most instances (n = 21, 39%), propofol was given for ≥24 h. Sometimes, however, the urine discoloration developed after propofol for ≤3 h (n = 12, 22%). Propofol-associated urine discoloration was usually observed during the administration of this agent, but it was at times (n = 11) first recognized ≥3 h after propofol discontinuation. The duration of green urine discoloration was usually ≤24 h after stopping propofol. Propofol-associated green urine discoloration was never associated with worsening kidney function. A pink-cloudy urine discoloration was observed in 32 subjects with an acidic urine pH and increased uric acid excretion given propofol for ≤24 h. A stage I acute kidney injury was observed in 2 cases (6.3%) of propofol-associated pink-cloudy urine discoloration. Nine cases of non-urinary green discoloration were observed: hair (n = 4), breast milk (n = 1), liver (n = 1), stool (n = 1).

CONCLUSION

Propofol is sometimes associated with a green (benign) or pink-cloudy (occasionally associated with mild acute kidney injury) urine discoloration. Rarely, non-urinary green discoloration has been reported.

Prognostic value of spot testing urine pH as a novel marker in patients with ST-segment elevation myocardial infarction

Aim: To investigate the relationship between urinary pH (UpH) and clinical outcome in patients with ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention. Methods: Data of 2081 patients with ST-segment elevation myocardial infarction were analyzed, including UpH. Patients were divided into UpH <6.0, 6.0≤ UpH <7.0 and UpH ≥7.0 based on UpH level. The primary outcome was in-hospital all-cause mortality and major adverse clinical events. Results: The incidence of in-hospital clinical outcomes was significantly higher in low UpH group. Multivariate analysis found low UpH (<6.0) was an independent predictor of in-hospital all-cause mortality (OR: 2.85) and major adverse clinical events (OR: 2.39). A Kaplan-Meier analysis showed long-term all-cause mortality was also significantly higher in low UpH group. The multivariate cox analysis demonstrated that low UpH was an independent predictor of long-term all-cause mortality (HR: 2.57). Conclusion: Low UpH is a simple, accessible and powerful marker of poor clinical outcomes in such patients.

Fructose increases risk for kidney stones: potential role in metabolic syndrome and heat stress

Background

Fructose intake, mainly as table sugar or high fructose corn syrup, has increased in recent decades and is associated with increased risk for kidney stones. We hypothesized that fructose intake alters serum and urinary components involved in stone formation.

Methods

We analyzed a previously published randomized controlled study that included 33 healthy male adults (40–65 years of age) who ingested 200 g of fructose (supplied in a 2-L volume of 10% fructose in water) daily for 2 weeks. Participants were evaluated at the Unit of Nephrology of the Mateo Orfila Hospital in Menorca. Changes in serum levels of magnesium, calcium, uric acid, phosphorus, vitamin D, and intact PTH levels were evaluated. Urine magnesium, calcium, uric acid, phosphorus, citrate, oxalate, sodium, potassium, as well as urinary pH, were measured.

Results

Ingestion of fructose was associated with an increased serum level of uric acid (p < 0.001), a decrease in serum ionized calcium (p = 0.003) with a mild increase in PTH (p < 0.05) and a drop in urinary pH (p = 0.02), an increase in urine oxalate (p = 0.016) and decrease in urinary magnesium (p = 0.003).

Conclusions

Fructose appears to increase urinary stone formation in part via effects on urate metabolism and urinary pH, and also via effects on oxalate. Fructose may be a contributing factor for the development of kidney stones in subjects with metabolic syndrome and those suffering from heat stress.

Trial registration

ClinicalTrials.gov NCT00639756 March 20, 2008.

Pink Urine Syndrome: A Combination of Insulin Resistance and Propofol

Pink urine syndrome is mostly seen in patients treated with propofol anesthesia. The pink color is attributed to the presence of large concentrations of uric acid (and pigment), which is excreted in large amounts when propofol is given. We describe a case of propofol-induced pink urine syndrome and perform a comprehensive, evidence-based review. We discuss prior case studies already published in the literature as we speculate on the pathophysiology and how it translates to a clinically relevant entity.

Urinary pH is a predictor of diabetes in men; a population based large scale cohort study

AIMS

Previous cross-sectional studies revealed that patients with type 2 diabetes were associated with low urine pH. However, the association between urinary pH and incident type 2 diabetes is still unclear. Thus, we investigated the association between urinary pH and incident type 2 diabetes.

METHODS

This is a 5-year observational study of 3119men. We divided participants into four groups according to quartile of urinary pH. Multivariate logistic regression analysis was performed to calculate adjusted odds ratios (ORs) and 95% CIs for incident type 2 diabetes. We adjusted for age, body mass index, smoking, exercise, alcohol consumption, hypertension, hypertriglyceridemia, low high-density lipoprotein cholesterol levels and impaired fasting glycaemia.

RESULTS

In the follow-up examination, 113men diagnosed as diabetes. The proportion of incident diabetes was 6.9% (case/N=22/318) in the lowest urinary pH group (urinary pH = 5.0), 3.4% (46/1366) in the second lowest group (urinary pH = 5.5), 3.5% (30/856) in the third lowest group (urinary pH = 6.0) and 2.6% (15/579) in the highest group (urinary pH≥6.5). The lowest urinary pH group was associated with the increased risk of incident diabetes compared to the other urinary pH groups (multivariate OR=1.91, 95% CI 1.05-3.36, p=0.033 for the second lowest, multivariate OR=1.99, 95% CI 1.05-3.71, p=0.036 for the third lowest and multivariate OR 2.69, 95% CI 1.30-5.72, p=0.008 for the highest urinary pH groups).

CONCLUSIONS

Low urine pH is an independent predictor of diabetes. We suggest that the urine pH can be an easy practical marker for diabetes.

Heat Stress Nephropathy From Exercise-Induced Uric Acid Crystalluria: A Perspective on Mesoamerican Nephropathy

Mesoamerican nephropathy (MeN), an epidemic in Central America, is a chronic kidney disease of unknown cause. In this article, we argue that MeN may be a uric acid disorder. Individuals at risk for developing the disease are primarily male workers exposed to heat stress and physical exertion that predisposes to recurrent water and volume depletion, often accompanied by urinary concentration and acidification. Uric acid is generated during heat stress, in part consequent to nucleotide release from muscles. We hypothesize that working in the sugarcane fields may result in cyclic uricosuria in which uric acid concentrations exceed solubility, leading to the formation of dihydrate urate crystals and local injury. Consistent with this hypothesis, we present pilot data documenting the common presence of urate crystals in the urine of sugarcane workers from El Salvador. High end-of-workday urinary uric acid concentrations were common in a pilot study, particularly if urine pH was corrected to 7. Hyperuricemia may induce glomerular hypertension, whereas the increased urinary uric acid may directly injure renal tubules. Thus, MeN may result from exercise and heat stress associated with dehydration-induced hyperuricemia and uricosuria. Increased hydration with water and salt, urinary alkalinization, reduction in sugary beverage intake, and inhibitors of uric acid synthesis should be tested for disease prevention.

Lower urinary pH is useful for predicting renovascular disorder onset in patients with diabetes

BACKGROUND AND OBJECTIVES

A lower urinary pH (UpH) is closely linked to diabetes. However, its relation to diabetic renovascular damage is unclear. This study aimed to identify the relationship between UpH and the exacerbation of diabetic renovascular disorders.

METHODS

This is a 10-year observational study targeting 400 outpatients with diabetes who registered in 2003. We investigated the relationship between UpH in 2003 and renovascular damage from 2003 to 2013.

RESULTS

A total of 350 participants were eligible for the analysis. During their 10-year outpatient treatment, a decrease was seen in glycated hemoglobin levels, blood pressure, and estimated glomerular filtration rates (eGFRs), and an increase was seen in their urinary albumin-creatinine ratios (ACRs), uric acid (UA) levels, and intima-media thickness (IMT). UpH negatively correlated with urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), body mass index, UA, and ACR, and positively correlated with eGFR. The results of a multiple regression analysis showed that the independent risk factors for UpH were 8-OHdG, UA, eGFR, and ACR. UpH also negatively correlated with the percent change in IMT (%IMT), the percent change in pulse wave velocity (%PWV), and the change in log ACR (Δlog ACR), and positively correlated with the percent change in eGFR. A multiple regression analysis revealed that UpH was an independent risk factor for the %IMT, %PWV and Δlog ACR. Obese patients with low UpH values frequently suffered from sleep apnea syndrome.

CONCLUSIONS

These results suggest that UpH is a useful marker for predicting the onset of renovascular disorder in patients with diabetes.